From d63a5a74dee87883fda6b7d170244acaac5b05e8 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 8 Dec 2006 02:36:17 -0800 Subject: [PATCH] [PATCH] lockdep: avoid lockdep warning in md md_open takes ->reconfig_mutex which causes lockdep to complain. This (normally) doesn't have deadlock potential as the possible conflict is with a reconfig_mutex in a different device. I say "normally" because if a loop were created in the array->member hierarchy a deadlock could happen. However that causes bigger problems than a deadlock and should be fixed independently. So we flag the lock in md_open as a nested lock. This requires defining mutex_lock_interruptible_nested. Cc: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/md.c | 2 +- include/linux/mutex.h | 2 ++ kernel/mutex.c | 9 +++++++++ 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index d2bcb410e3a..3ce7a5d81d8 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4423,7 +4423,7 @@ static int md_open(struct inode *inode, struct file *file) mddev_t *mddev = inode->i_bdev->bd_disk->private_data; int err; - if ((err = mddev_lock(mddev))) + if ((err = mutex_lock_interruptible_nested(&mddev->reconfig_mutex, 1))) goto out; err = 0; diff --git a/include/linux/mutex.h b/include/linux/mutex.h index b2b91c47756..a7544afd758 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -125,8 +125,10 @@ extern int fastcall mutex_lock_interruptible(struct mutex *lock); #ifdef CONFIG_DEBUG_LOCK_ALLOC extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); +extern int mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass); #else # define mutex_lock_nested(lock, subclass) mutex_lock(lock) +# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) #endif /* diff --git a/kernel/mutex.c b/kernel/mutex.c index 8c71cf72a49..e7cbbb82765 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -206,6 +206,15 @@ mutex_lock_nested(struct mutex *lock, unsigned int subclass) } EXPORT_SYMBOL_GPL(mutex_lock_nested); + +int __sched +mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) +{ + might_sleep(); + return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass); +} + +EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); #endif /*